Opened 3 years ago

Closed 3 years ago

#24702 closed defect (fixed)

Intersections and saturations of FreeQuadraticModules have the wrong ambient module

Reported by: sbrandhorst Owned by:
Priority: critical Milestone: sage-8.2
Component: linear algebra Keywords:
Cc: pmenegat Merged in:
Authors: Simon Brandhorst Reviewers: David Roe
Report Upstream: N/A Work issues:
Branch: 0dd7769 (Commits, GitHub, GitLab) Commit: 0dd77697a542a4b46a5e874a87729e08971d3a74
Dependencies: Stopgaps:

Status badges

Description (last modified by sbrandhorst)

sage: L = FreeQuadraticModule(ZZ,2,matrix.identity(2))
sage: S1 = L.submodule([(1,0)])
sage: S2 = L.submodule([(0,1)])
sage: S1.intersection(S2).ambient_module()
Ambient free module of rank 2 over the principal ideal domain Integer Ring

Thus the intersection changes the ambient module. And in particular the inner product. This breaks other things like fgp modules too.

The same holds for saturations.

Change History (8)

comment:1 Changed 3 years ago by sbrandhorst

  • Priority changed from major to critical

comment:2 Changed 3 years ago by sbrandhorst

  • Branch set to u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module

comment:3 Changed 3 years ago by sbrandhorst

  • Branch u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module deleted
  • Description modified (diff)
  • Summary changed from Intersections of FreeQuadraticModules have the wrong ambient module to Intersections and saturations of FreeQuadraticModules have the wrong ambient module

comment:4 Changed 3 years ago by sbrandhorst

  • Branch set to u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module

comment:5 Changed 3 years ago by git

  • Commit set to 0dd77697a542a4b46a5e874a87729e08971d3a74

Branch pushed to git repo; I updated commit sha1. New commits:

0dd7769Indentation

comment:6 Changed 3 years ago by sbrandhorst

  • Status changed from new to needs_review

comment:7 Changed 3 years ago by roed

  • Reviewers set to David Roe
  • Status changed from needs_review to positive_review

Looks good to me. Patchbot failures seem spurious.

comment:8 Changed 3 years ago by vbraun

  • Branch changed from u/sbrandhorst/intersections_of_freequadraticmodules_have_the_wrong_ambient_module to 0dd77697a542a4b46a5e874a87729e08971d3a74
  • Resolution set to fixed
  • Status changed from positive_review to closed
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